CA2177798A1 - Stabilizers for high nitrile multipolymers - Google Patents

Abstract

A melt processable high nitrile multipolymer such as an acrylonitrile olefinically unsaturated multipolymer, which is stabilized by admixing with a maleic acid and its derivatives, maleic anhydride, maleamides, maleates and combinations thereof.

Description

THE S?ECIFICATION

STAB~LIZERS FOR HIGH NITRILE
MULTIPOLYMERS

BACKGR~OU~D OF THE INVENTION
Related Application This patent application is a continuation-in-part of patent application entitled "Stabilizers for High Nitrile Multipolymers~, USSN
08/~94,833 and ~lled on June 26, 1995, which is a continuation-in-part of patent application entitled "Stabilizers for Acrylonitrile/Methac~lonitrile Multipolymers", USSN 08jl71487 and filed on Oecember 21, 1993.

~ield of the Invention 3 o The present invention relates to a stabilizer composition for high nitrile multipolymers, in particular an acrylonitrile olefinica!ly unsaturated multipolymer and the like and a method for stabilizing the high nitrile multipolymer. More particularly, the invention relates to the stabilization of an acrylonitrile ole~lnically unsaturated 3 5 multipolymer and the like against thermal degradation, melt processing conditions and heat discoloration by the inclusion of maleic acid and its derivatives, salts of maleic acid, maleic 2~ 7779~
-anhydrides, malean-lides and its salts and maleates and its salts into the nitrile multipolymer. It is understood that the telm multipolymer includes copolymers, terpolymers and multimonomer polymers throughout this specification.

Description of the Prior Art Nitlile polymers have excellent physical, therrnal and 10 mechanical properties such as barner properties, chemical resistance, rigidity, heat resistance, UV resistance, moisture retention and bacteria resistance. Acrylic polymers are high nitrile polvmers that are desirable in the production of fibrous textiles, filrns, molded ~?bjects, pack~ging applications and the like.
However, acrylic polymers and other high nitrile multipolymers having long repeating sequences of the same nitrile monomer unit, in particular an acrylonitrile monomer unit, are known to degrade when heated and processed by commercial methods. The long sequences of nitrile monomer units make the 20 acrylic polymers non-processable without the use of a solvent l)ecause the polymer degrades at an ever increasing rate above 150C. The acrylic polymer further becomes yellow, orange, red and eventually black as it degrades.
An acrylonitrile olefinically unsaturated multipolymer is 25 disclosed in USSN 08/387,303 entitled A Process for ,~akiI1g a High Nitrile Multipolymer Prepared ~rom Acrylonitrile and Olefinically Unsaturated Monomers." An acrylonitrile/methacrylonitrile copolymer is ~iscl~sed in USSN 08/150,515 entitled A Process for Making a Polyrner of Acrylonitrile, Methacrylonitrile and (~lefinically \
\ 21 7779~

Unsaturated Monomers and a multipolymer of acrJlonitrile/methacrylonitrile/olef nically unsaturated monomer is disclosed in USSN 08/14g,8~0 entitled A Process for Making an Acrylonitrile/ Methacrylonitrile Copolymer.~ The 5 acrylonitrile~methacrylonitrile multipolymers are thermally processed without the use of ~olvents io yield acrylic fibers.
~owever, the multipolymers are subject to thermal degradation albeit not as severely as the commercial acrylic fiber polymèr.
Thermoplastic nitrile barrier polymer resins are known in the 10 art and have been described m United St~s Patent Nos. 3, 426,102;

3,586,737 and ~,106,925. These nitrile polymers are known to have desirable barrier prvperties and chemical resistance. However, these thermoplastic nitrile polymers while melt-processable are difficult to process.
It is advantageous to reduce the thermal degradation and prevent thermal discoloration of high nitrile muitipolymers. There is a need to readily melt process an acrylonitrile olefinically unsaturated muitipolymer and the like without thermal degradation, thermal discoloration and decrease of the viscosity of the high nitrile 2 o multipolymer.
It has been discovered that maleic acid and its derivatives ~E~R ;~ 5 and its salts, maleic anhydrides, maleamides and~ salt's' ar.d `R ~ ~ ~sl~lq~ r~
maleat~s and ~salts greatly reduce thermal degradation, thermal discoloration and decrease the viscosity when added o a high nitrile 25 multipolymer, in particular an acrylonitrile olefirlically unsaturated multipolymer.
U.S. Pat. No. 3,954,913 entitled "Stabilized Nitrile Polymers and U.S. Pat. No. 3,984,499 entitled ~Therrnally Stable High Nitrile Resins and Methods for Producing the Same" both assigned to The 21 7779~

Standard Oil Compan3r relate to nitrile poi~-mers, in particular a Barex~ polymer which is a 75:25 acrylonitrile/methyl acrylate polymer conta~ning 5% ~o 25% of an elastomeric component. The patents disclose that the nitIile polymer can be stabilized a~ainst 5 the~rnai discoloration by certaln derivatives of maleic acid, in particular mono-esters of certain organic polycarboxylic acids. It has been reported by F`aserforschun~ und Textiltechnik, Volume 21, No.
3 '1970~, that maleic acid and some of its derivatives are useful inhibitors against thermal discoioration of a nitrile polymer. Further, 10 it states that the complete indifference of the maleic acid esters" for the stabilization of nitrile polymers. U.S. Patent No. ~,520,847 discloses that naleimides and derivatives thereof are therrmal and anti-discoloration agents for acrylonitrile polymers and copolymers.
The article and the patents do not disclose nor suggest the use of 5 maleic ac.d and its derivatives, maleic acid and its salts, maleic ,~ 14 ~ 6.e ~ c,~/h~u~
anhydrides, rnaleamides and ~ salts, and maleates and itg salts for the reduction of therrnal degradation and maintenance of melt processability of a high nitrile polymer.
It is advantageous to reduce the thermal degr~dation and 20 thermal discoloration-of high nitrile multipolymers by the stabilizer composition of the present invention. The stabili~er composition reduces melt viscosity and prevents further increases of viscosity of the high nitrile rnultipolymer during melt processing. Further, the stabi]izer composition of the present invention reduces crosslinking 25 and molecular weight build-up of the high nitrile multipolymer during melt processing. Additionally, color development of the nitrile rmultipolylner duling thermal processing is ret~-ded.

21 7779~

Summ~uy of the Invention A stabilizer composition for a high nitrile multipolymer comprises maleic acid and its derivatives, maleic acid and its salts, 5 maleic anh~dride, maleamides and their salts, and rnaleates and the;r salts. The inclusion of the stabilizer composition in a high nitrile multipolymer reduces therrnal degradation, discoloration, molecular weight growth and cross-linking which lead to intractability and increased melt v;scosity of the multipolymer.
The present invention relates to a composition comprising a melt processable high nitrile multipolymer said multipolymer being in admixture with a stabilizer composition comprising maleic acid and its derivatives, maleic acid and its salts, rnaleic anhydride, malearnides and their salts, maleates and their salts and combinations thereof and wherein the stabilizer composition reduces thermal degradation, reduces the rate of increase of melt viscosity during therrnal processing and reduces thermal discoloration of the high nitrile multipolymer.
The process of the present invention produces a thermally 2 o stable nitrile multipolymer, in particular a thermally stable acrylonitrile olef;nically unsaturated multipolymer. The thermally stable nitrile multipolyrner may be ~urther processed by spinning into fibers, injectiorl molding, extrusion, blow extrusion, blow molding and the like.
2:) Detailed Description of the Invention The present invention relates to a stabilizer composition for a high nitrile multipolymer, in particular an acrylonitrile olefinically 21 7779~
, unsaturated multipolym.er, &nd a method for stabilizing the high nitrile mul~ipolymer. The novel stabilizer compositioIl is co.npatible with the nitrile multipolymer.
The stabili~er composition for addition into the high nitrile 5 multipolymer includes but is not !imited to maleic acid and its derivatives, maleic acid and its salts, maleic anhydride, malearnides and their salts, and maleates and their salts. The preferred stabilizer compositior,s maleates and their salts.
The salts of maleic acid include but are not limited to the io salts found in Group IIA and IIIB of the Periodic Table of Elements, salts of organic bases such as amines, and the like. Useful amines include, but are not limited to, prim~ry, secondary and tertiary alkyl and aryl amines cont~inin~ Cl through Cl8. Calcium and rnagnesium are the preferred salts. The salts can be used alone or in 5 combination.
The maleates include but are not limited to esters of maleic acid of the formula:

2 o }iC====CH
O=C C=O
OR OR
:~5 wherein each R is indepelldently selected from hydrogen ~H), C4 to Clg alkyl group, ars-l group, alkyl substituted C7 to ~24 ar~l group and combinations thereof. Exemplary- esters of maleic acid are alkyl 30 half esters of maleic acid, diesters of maleic acid, cetyl maleate, di-cetyl maleate, octyl maleate, di-octyl m~leate, lauryl maleate, di-lauryl maleate, butyl maleate, di-butyl maleate, hexadecyl maleate, di-hexadecyl maleate, 2-ethylhexyl maleate, di-2-ethylhexyl maleate, phenyl maleate, di-phenyl maleate, tridecyl maleate, di-tridecyl maleate, octadec:yl maleate, di-octadecyl maleate and tne like. The preferred maleates are lauryl maleate, tridecyl maleate, octadecyl 5 maleate, and hexadecyl maleate.
The salts of maleates include, but are not limited to, the salts found in Group ILA and IIIB of the Periodic Table of Elements, salts of organic bases such as amines and the like. Use~ul amines include, but are not limited to, plimar y, secondary, and tertiary alkyl 0 and aryl amines c ontaining C, through (~l~. T~le prefcrred salts are calcium and magnesium. The salts can be used alone or in combination.
The maleamides include, but are nct limited to, maleic acid monoamide of the fornlula HO-CO-C=C-CO-NH-R and maleic acid 5 diamide of the formula R-NH-CO-C-C-CO-NH-R wherein R is independerltly selected from, hydrogen (H), C4 to Cl~ alkyl group, aryl group, alkyl substituted C7 to C2~ aryl group and combinations thereof. The maleamides include mono-alkyl amides of maleic acid, di-alkyl amides of maleic acid, mono-aryl amides of maleic acid, di-20 arylamides of maleic acid and the like. Exemplary maleamides arecetyl maleamide, di-cetyl maleamide, octyl maleamide, di-octyl maleamide, lauryl maleamide, di-lauryl maleamide, butyl maleamide, di-butyl maleamide, hexadecyl maleamide, di-hexadecyl maieamide, 2-et'nylhe.Yyl maieamide, di-2-ethylhexyl maleamide, phenyl 25 maleamide, di-phenyl maleamide, tridecyl maleamide, di-tridecyl maleamide, octadecyl maleamide, di-octadecyl rnalea~nide and the like.
The salts of the rnaleimides include, but are not limited to, the salts found in Group IIA and IIIB of The Periodic Table of 2 ~ 77798 ElemeIllS, salts OI organic bases such as ~nines, and the like.
Useful amines include, but are not limited to, primary, secondary, tertiary alkyl and aryl arnines containing Cl through Cl8. The preferred salts are calcium and magnesium. The salts can be used 5 alone or in combinations.
The stabilizer composition can be used alone or in combination. The stabilizer composition can also be used with other additiYes such as plasticizers, pigments, anti-oxidants, fillers, dyes, delustrants and the like depending on the properties desired to 10 impart to the high nitrile multipolyrner.
The stabilizer composition of the present invention is effective at low concentrations. The stabilizer composition is added to the high nitrile multipolymer in the range of about ~.1% to about 10% by weight, preferably about 0.2% to about 5% and most preferably about 0.3% to about 3% by weight of the nitrile multipolymer.
The stabilizer composition is a liquid or a solid and~ may be added to a nitrile multipolymer as a powder, a liquid, an emulsion, or a solution. The stabilizer composition of the present invention is 2 o typic~lly added to the high nitrile multipolymer subsequent to the polymerization reaction. For example, the scabilizer composition, as an emulsion in water, may be added to the high nitrile multipolymer emulsion latex or suspension slurry prior to the isolation of the multipolymer, i.e. the coagulation step and subsequent: processing.
25 The stabilizer composition, as a powder, a liquid, a solution, or an emulsion may be added by dry blending with the isolated multipolymer strands or powder and the resulting blends can be pelletized and/or extruded into ~lbers, sheets or other shapes.

E~emplaly high nitrile multipolymers are a nitrile multipolymer comprising an acrylonitriie rmonomer and one or more ole~lnically unsaturated monomers that are polymerized to produce a mel~ processable acrylonitrile olefinically unsaturated multipoiymer.
The olefinic~ly unsaturated monomer employed is any olefinically unsaturated monomer with a C=C double bond polymerizable with an acIylonitrile monomer.
The olefirlica]ly unsaturated monomer includes but is not limited to acrylates and their derivatives, methacrylates and their derivatives, acrylamide and its derivatives, methacrylamide and its deAvatives, vinyl esters, vinyl ethers, vinyl amides, vinyl ketol~es, styrene and its derivatives, halogen containing monomers, ionic monomers, acid containing monomers, base containing monomers, olefins and the like. The olefinically unsaturated monomer can be one or more monomers from one or more groups of the olefinically unsaturated monomers. Thus, there can be more than one olefinically unsaturated monomer polymerized with the acrylontrile monomer.
The acrylates include but are not limited to C1 to C12 alkyl, alyl and cyclic acrylates such as methyl acrylate, ethyl acrylate, phenyl ac~ylate, butyl acrylate, isobornyl acrylate and 2-ethylhe~yl acrylate and functional derivatives of the acrylates such as 2-hydroxyethyl acrylate, 2-chloroethyl acrylate and the like. The preferred acrylates are methyl acrylate and ethyl acrvlate.
The methacrylates include but are not lirnited to Cl to C12 alkyl~ aryl and cyclic methacrylates such as methyl methacrylate, ethyl methacrylate, phenyl methacrylate, butyl methacrylate, isobornyl methacrylate and 2-ethylhexyl methacrylate and functional deri~ati~-e3 of the methacrylates such as 2-hydroxyethyl methacrylate, 2-chloroethyl methacrylate and the like. The pre~erred methacrylate is rnethyl methacrylate. The methacrJlate derivatives include methacrylonitrile.
The acrylamides and methacrylamides and each of their N-5 substituted alkyl and aryl derivatives include but are not limited toacrylamide, methacrylamides, N-methyl acrylamide, N, N-dimethyl acrylamide and the like.
The vinyl esters include but are not limited to vinyl acetate, propionate, butyrate and the like. The preferred vinyl ester is vinyl 0 acetate.
The vinyl ethers include but are not limited to C1 to C8 vinyl ethers such as ethyl vinyl ether, butyl vinyl ether and the like.
The vinyl amides include but are not limited to vinyl pyrrolidone and the like.
The vinyl ketones include but are not limited to C1 to C8 vinyl ketones such as ethyl vinyl ketone, buty' vinyl ketone and the like.
The styrenes include but are not limited to styrene, indene and a styrene of the formula ~CA=CI~
/ B
'O
\fc wherein each of A, B, C, and D is independently selected from hydrogen (H) and C1 to C4 alkyl group for exarnple methylstyrenes, 25 substituted styrenes, multiply-substituted styrenes and the like.

2~ 77798 The halogen containing monome. s include but are not limited to vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene bromide, vinylidene fluoride, halogen substituted propylene monomers and the like. The preferred halogen containing rnonomers are vinyl bromide and vinylidene chloride.
The ionic monomers-include but are not limited to sodium vinyl suifonate, sodium styrene sulfonate, sodium methallyl sulfonate, sodium acrylate, sodium methacrylate and the like. The preferred ionic monormers are sodium vinyl sulfonate, sodium styrene o sulfonate and sodium methallyl sulfonate.
The acid containing monomers include but are not limited to acrylic acid, methacrylic acid, vinyl sulfonic acid, itaconic acid, styrene sulfonic acid and the like. The preferred acid containing monomers are itaconic acid, styrene sulfonic acid and vinyl sulfonic acid.
The base containing monomers include but are not limited to vinyl pyridine, 2-aminoethyl-N-acrylamide, 3-aminopropyl-N-acrylamide, 2-aminoethyl acrylate, 2-aminoethyl methacrylate and the like.
2c The olefins include but are not limited to isoprene, butadiene, C2 to C8 straight chain and branched alpha-olefins such as propylene, ethylene, isobutylene, diisobutylene, l-butene and the like. ~he preferred olefins are isobutylene, ethylene and propylene.
Examples of a high nitrile multipolymer include but are not limited to acrylonitrile olefinicaliy unsaturated multipolymer, acrylonitrile/methacrylonitrile/olefinically unsaturated multipolymer, acrylonitrile/methacrylonitrile multipolymer and the like. The preferred high nitrile multipolymer is an acrylonitrile olefinically unsaturated multipolymer.

Exemplary methods to make acrylonitrile olefinically unsaturated multipolymer are described in USSN 08/387,303 entitled ~A Process for Makin~ a High Nitrile Multipolymer Prepared Fro~n Acrylonitrile and Oiefinically Unsaturated Monomers", an 5 acrylonitrile/mel:hacrylonitrile multipolymer is described in USPN
5,106,~25 entitled "Preparation of Melt-Processable Acrylonitrile/Methacrylonitrile Copolymers~, and USSN 08/149,880 entitled ~A Process for Making an Acrylonitrile/Methacrylonitrile CopolymeP and an acrylonitrile/methacrylonitrile/olefinically 0 unsaturated multipolymer is described in US3N 08/150,515 entitled A Process for Making a Polymer of Acrylonitrile, Methacrylonitrile and Olefinically Unsaturated Monomers. All four applications are assigned to The Standard Oil Company and incorporateA herein.
The nitrile multipolymer can be prepared by any known method such as an emulsion, a solution, a suspension or in continuous addition bulk process. The polymerization process is generally carried out as an aqueous emulsion or suspension process in the presence of a multimonomer feed mixture of an acrylonitrile monomer and an olefinically unsaturated monomer; a surfactant or 20 suspending aid; optionally a molecular weight modifier; and a free radical initiator at a temperature in the range of about 40C to 120C
in the substantial absence Or molecular oxygen. The acrylonitrile olefinically unsaturated mu]timonomer feed mixture contains about 95% by weight to about 20% by weight aclylonitrile monomer, 80%
by weight to about 5% by weight olefinically unsaturated monomer The polymerization process is carried out by continuous or incrernental addition of each of the reactants.
The reaction is continued until po]ymerization has proceeded to the desired extent, generally from about 40% to about 99%
J~

con-rersiQn and prefer~bly from about 70% ~o about 95% conversion.
The high nitrile multipolymer generally contains ~0% by weight to about 95% by weight polymerized acrylonitrile and about 5% by ~,veight to about 50% by weight polymerized olefinicaliy unsaturated 5 monomer.
At the conclusion of the polymerization reaction the acrylonitrile olefinically unsaturated multipolymer is isolated as a slurry, or a latex. Any known technique may be used to isolate the acrylonitrile olefinically unsaturated multipolymer such as crumb o coagulation, spraying the solution of the multipolymer into a heated and/or evacuated chamber to remove the water vapors, stripping, filtration, centrifugation and the like.
The high nitrile multipolymer has reduced thermal degradation, reduced thermal discoloration and exhibited less "ELr viscosity increase in subsequent thermal processing steps due to the presence of the stabilizer composition in the high nitrile multipolymer.
The high nitrile multipolymer with the stabilizer composition may be prosessed into a wide variety of useful articles by thermal 20 melt spinning, extrusion in the absence of solvent and in the absence of water, injection molding, calendering, vacuum forming, milling, molding, drawing, blowing and the like. The use of the stabilizer reduces thermal degradation, discoloration, cross-linking and melt viscosity increase of the nitrile multipolymer products during the 25 thermoprocessing of the nitrile multipolymer.

21 7779~

SPECIFIC EMBODIMENTS

The following examples demonstrate the process and 5 advantages of the present invention.

Multipolymer r~e~alation Equipment A 50 gallon circulating hot water jacketed stainless steel reactor was equipped with a reflux condenser, thermocouple/controller, a turbine agitator, nitrogen gas inlet line, vacuum line, and two monomer feed stream pumps. The two 15 monomer feed mixtures were metered, as separate single solutions, by constant feed pumps.

Procedure 2 o The reactor was initially charged with about 293 lbs. of distilled water, about 2.75 lbs. of Rhofac RE-610, about 0.85 lbs. of N-octyl mercaptan, about 7.04 lbs. of acrylonitrile monomer and about 2.96 lbs. of methacrylonitrile monomer. The reactor was then purged with nitrogen and heated to about 60C. After temperature was obtained, a slurry containing 0.47 lbs. of the initiator Vazo 52, about two lbs. of water and about 0.25 lbs. of Rhofac RE-6 10 was added along with two separate monomer feed streams. The first monomer feed was composed of about 70.4 lbs. of acrylonitrile and about 29.6 lbs. of methacrylonitrile and fed to the reactor at a i4 uniforrm rate over a period of about 270 minutes. The second monomer ~eed was pure methacrylonitrile-which was fed to the reactor at about 0.0222 lbs/min. for about the first 90 minutes, at about 0.0356 lbs/min. from about 90 to about 180 minutes and finally at a rate of 0.113 lbs./min. for about 180 to about 270 minutes. During the course of the reaction, about 1.19 lbs of N-octyl mercaptan was added at about 90 minutes and at about 180 minutes.
At the end of the reaction (about 270 minutes) the reaction o was stripped of unreacted monomer by vacuum stripping at about 60C for about three hours. The latex was then coagulated with alum solution at about 81C to about 85C and washed with water at about 75C, and dried. The result was a course, free flowing, white polymer powder, designated polymer A. The multipolymer composition of A was 54%(wt.) acrylonitrile and 46%(wt.) methacrylonitrile with a molecular weight of 143,000.

Preparation of Mono Esters of Maleic Acid 2 o Maleate monoesters were prepared by reacting equal molar quantities of an alcohol and maleic anhydride under anhydrous conditions. For example, monolauryl maleate was prepared by reacting about 5.27 moles of lauryl alcohol (l-dodecanol), with about 5.27 moles of maleic anhydride. The alcohol was melted in about a 50C air oven, weighed, and poured into a jacketed glass 2 liter reactor which had been preheated to about 50C. The crushed maleic anhydride was added to the melted alcohol and stirring was started. The reactor was fitted with a 3" 4-bladed Teflon paddle rotating at about 350 rpm. The reactor was open to the atmosphere ,_ 2 ! 77798 via a port which was fitted with a drying tube containing anhydrous CaS04. Heat was supplied to the reactor by circulating water, from a thermostatic~lly controlled bath, through the jacket. After about 25 minutes the temperature of the reaction mixture was increased to 5 about 60C. The appearance of the reactants changed from a slurry to a hazy liquid to, finally, a clear colorless liquid. After another hour the temperature was increased to about 70C. Thirty minutes later the temperature was raised to about 80C~, where it remained for the balance of the 6 hour total reaction time. The liquid product was o poured directly from the reactor, without cooling, into a series of shallow trays, where the liquid was allowed to cool and solidify. The product was broken up and bottled. About 1516.6g product was obtained resulting in about a 99.43% recove~r. NMR analysis of the product showed the product consisted of about 94.2% monolauryl maleate, about 3.7% dilauryl maleate, about 1.0% maleic acid, and about 1.1% lauryl alcohol.

Stabilizer Addition Procedure: -20 Powder Blending:

Finely divided stabilizer is dry blended with polymer powderby any effective mixer. For example, about 1.04 gms. of the stabilizer that has been ground in a mortar and pestle to a powder is added to about 50.96 gms of polymer. This powder was blended on a roll-mill for 3 hours before being subjected to melt processing evaluation.

i6 2 t 777~8 Latex Blendin~:

An aqueous emulsion of the stabilizer is mixed with the 5 polymer latex and the two are co-coagulated to yield an intimately mixed stabiliær/polymer crumb. A stabilizer emulsion was prepared by heating a mixture of about 10 gms lauryl maleate and about 2 gms of Dowfax 2A (emulsifier manufactured by Dow Chem. Co.) to about 60C until homogeneous. To the mixture was added about 88 10 gms. of about 60C water gradually with stirring. The pH of the mixture was then adjusted to 6 by the addition of ammonium hydroxide yielding a low viscosity, translucent emulsion. This stabilizer emulsion can be added in the desired amount to the polymer latex to achieve the needed level.
Testing Procedure:
Brabender Plasticorder:

The Brabender plasticorder is a low shear melt mixing device 2 o that measures the torque (m-gms~ required to melt stir a molten - polymer and is manufactured by the Brabender Instrument Co., S. Hackensack, NJ. The Brabender Plasticorder is routinely used to judge the melt processability of Barex~ resins as a quality control measure. It can easily determine whether a polymer can be melted 25 and processed on normal thermoplastic equipment. Brabender analyses were run at about 200C with torque readings taken at about 5 minute intervals to about 30 minutes. This method measures polymer degradation as a function of time, temperature, and physical abrading.
/~

Color:

About 1 gram of multipolymer sample with stabilizer is 5 withdrawn from the Brabender after 10 minutes and again after 30 minutes. Each sample is dissolved in dimethylformamide (DMF) to make a 5.0% by weight solution in the DMF. Each solution is then compared to the Gardner Color Standards for Liquid 1953 Series, made by Gardner Laboratory, Inc., Bethesda, Maryland. The Color 0 Standards for Liquid describes color on a scale of 1 to 18, wherein 1 describes a colorless liquid and 18 describes a beer bottle brown color.

Stabilizer Evaluation: -Example 1: Polymer A

Dry blends were prepared from Polymer A and various maleic 20 acid derivatives at the 2% (by weight) level. These blends were subjected to Brabender plastication and torque measurements at about 200~C at about 35 rpm. ~mnll ~.nm~ v~ w;lh Law~
~OI~t 1n ~b~ 0 ~nd ~ul 3A .~ ~tcs for ~n~1~3i~r The torque required to masticate the melt, a measure of melt viscosity, was 2 5 reported in meter-grams (m-gm).

Table I
Tor~ue (m-gm), 200C
Sample Composition 10 min. 20 min. 30 min.
PolymerA (blank) 2632 2739 3494 ~Ialeic acid 2611 :2842 3058 Maleic anhydride 2243 2446 2536 Cetyl maleate 828 782 748 Lauryl maleate 833 773 839 Di-2-ethylhexyl rnaleate 1271 1493 1782 Maleimide 2163 2420 2548 Phenyl maleimide 2207 2295 2278 The above results demonstrate that the addition of the stabilizer composition in the acrylonitrile/methacrylonitrile multipolymer reduces the initial melt viscosity and retards its growth during the melt processing. For instance, lauryl maleate and cetyl maleate in the nitrile multipolymer show essentially no viscosity increase in about 30 minutes at about 200''C. The above comparison of stabilizers demonstrate that the maleates are unexpectedly better than the maleimides.

Example 2: Polymer B, Mono Maleate Ester Evaluation:

Polymer B of the same AN/MAN composition as Polymer A but having a molecular weight of 69,000 was dry blended with various maleate mono esters and subjected to Brabender plastication at about 200C and about 35 rpm.
Dry blends were prepared from the polymer B and various maleic acid derivatives at the 2% (by weight) level. These blends were subjected to Brabender plastication and torque measurements at about 200C at about 35 rpm. The torque required to masticate the melt, a measure of melt viscosity, is reported in meter-grams (m-gm).

TABLE ll Torque (m-gm), 200C
Sampl~ Composition 10 min. 20 min.30 min.
Polymer B 1883 22722540 2-Ethylhexyl maleate 966 12431780 Nonyl maleate 1570 23273125 Decyl maleate 1046 13492343 Lauryl maleate 731 806 951 Hexadecyl maleate 752 793 995 Octadecyl maleate 827 10691842 Phenyl maleate 1362 17772125 Dodecyl mercaptan maleate 1362 1777 2132 The above results demonstrate that mono maleates effectively reduce initial melt viscosity and retard viscosity increases 2 o of the nitrile multipolymer during melt processing.
Example 3 A dry polymer comprising about 85% acrylonitrile (AN) and 25 about 15% methyl acrylate (MA) and dry stabilizer were intimately mixed on a roll mill for about 2 hours at room temperature. The torque required to masticate the melt, a measure of melt viscosity was reported in meter-grams (m-gm), color measurements were made and a maleimide stabilizer was compared to the maleates, and the 30 results are set forth in Table III.

Example 4 3 5 A dry polymer comprising about 85% acrylonitrile and about 15% ethyl acrylate (EA) and dry stabilizer were intimately mixed on a roll mill for about 2 hours at room temperature. The torque required to masticate the melt, a measure of melt viscosity was reported in meter-grams (m-gm) and color measurements were made, and the 4 o results are set forth in Table III.

21 777~8 Example 5 A dry polymer comprising about 85% acrylonitrile, about 7%

5 methyl methacrylate (MMA) and about 7% methyl acrylate and dry stabilizer were intimately mixed on a roll mill for about 2 hours at room temperature. The torque required to masticate the melt, a measure of melt viscosity was reported in meter-grarns ~m-gm) and color measurements were made, and the results are set forth in Table 10 III.

Example 6 A dry polymer comprising about 75% acrylonitrile and about 25% methyl methacrylate and dry stabilizer were intimately mixed on a roll mill for about 2 hours at room temperature. The torque required to masticate the melt, a measure of melt viscosity was reported in meter-grams (m-gm) and color measurements were made, 2 o and the results are set forth in Table III.

Example 7 A polymer comprising about 85% acrylonitrile and about 15% methyl acrylate was prepared by a continuous feed emulsion process and recovered as described for polymer A. Dry stabilizer was added to the polymer and intimately mixed mechanically. The torque required to masticate the melt, a measure of melt viscosity was reported in m-gm and color measurements were made. The results are set forth in Table III and demonstrate lowered final torque values and improved ~lnal color.

~/

2 ! 77798 r -g.' o o ._ F ~ 1~ 1~ o~ u~ N N N ~r) ct> ~ (D a) CJ~ 't O ~ ~
O 0~ ~ o N n ~ a) ~ 1~ ~ O O <~ ~
m ~ ) 0 - o 0 m .

IL .' ~ m ~ .
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m N~ ~ ~O~ ~N~ N~_~

m E ~ o O O O O O O O O O O O O O O O O O
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- NN N NNNNN NNNNN NNNNN
m m ~ ca O C ~ ~ C~ C~ C _ O ~ C ~
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'Q~ C~ E ~ ~ c w c c O o ~ c c _ c 'I:
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2 t 77798 C ~

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m E

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F _~ o o O O O
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o 3 -., 2 1 7779~

The above results demonstrate that the inclusion of the stabilizer into the nitrile multipolymer greatly reduces viscosity of the nitrile multipolymer during melt processing. Further, the above table 5 demonstrates that the color is better with the inclusion of the stabilizer into the nitrile multipolymer.
Additionally, Example 3 compares the stabilizer lauryl maleate to phenyl maleimide. The data demonstrates that the lauryl maleate is unexpectedly better in color and initial melt torque than 10 the phenyl maleimide. It is unexpected that the lauryl maleate is a better stabili7er for a high nitrile multipolymer than the phenyl maleimide.
From the above description and examples of the invention those skilled in the art will perceive improvements, changes and modifications in the invention. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims.

Claims (10)

1. A composition comprising a melt-processable high nitrile multipolymer being in admixture with a stabilizer composition said stabilizer composition comprising maleic acid and its derivatives, salts of maleic acid, maleic anhydride, maleamides, salts of maleamides, maleates, salts of maleates, and combinations thereof and wherein said stabilizer composition reduces thermal degradation, decreases melt viscosity during thermal processing and reduces thermal discoloration of the high nitrile multipolymer.

2. The composition of claim 1, wherein said salt is selected from the group consisting of beryllium, magnesium, calcium, strontium, barium, aluminum, salts of organic bases consisting of primary, secondary and tertiary alkyl and aryl amines containing C1 through C18 and combinations thereof.

3. The composition of claim 2, wherein the salt of maleic acid is selected from the group consisting of calcium, magnesium, and combinations thereof.

4. The composition of claim 5, wherein the maleates comprise esters of maleic acid of the formula:

wherein each of R is independently selected from hydrogen (H), C4 to C18 alkyl group, aryl group, alkyl substituted C7 to C24 aryl group and combinations thereof; and wherein the maleate is selected from the group consisting of monoester of maleic acid, diester of maleic acid, cetyl maleate, di-cetyl maleate, tridecyl maleate, di-tridecyl maleate, octyl maleate, di-octyl maleate, lauryl maleate, di-lauryl maleate, butyl maleate, di-butyl maleate, hexadecyl maleate, di-hexadecyl maleate, 2-ethylhexyl maleate, di-2-ethylhexyl maleate, phenyl maleate, di-phenyl maleate, octadecyl maleate, di-octadecyl maleate and combinations thereof; and wherein the maleamide is selected from the group consisting of mono-alkyl amides of maleic acid, di-alkyl amides of maleic acid, mono-aryl amides of maleic acid, di-aryl amides of maleic acids and combinations thereof.

5. The composition of claim 1, wherein the maleamide is selected from the group consisting of cetyl maleamide, di-cetyl maleamide, octyl maleamide, di-octyl maleamide, lauryl maleamide, di-lauryl maleamide, butyl maleamide, di-butyl maleamide, hexadecyl maleamide, di-hexadecyl maleamide, 2-ethylhexyl maleamide, di-2-ethylhexyl maleamide, phenyl maleamide, di-phenyl maleamide, tridecyl maleamide, di-tridecyl maleamide, octadecyl maleamide, di-octadecyl maleamide and the like.

6. The composition of claim 1, wherein the stabilizer composition is selected from the group consisting of lauryl maleate, hexadecyl maleate, cetyl maleate, tridecyl maleate, octadecyl maleate, calcium maleate, calcium lauryl maleate, magnesium lauryl maleate, strontium lauryl maleate, calcium tridecyl maleate, C18 amine maleate salt, and combinations thereof.

7. The composition of claim 1, wherein said acrylonitrile olefinically unsaturated multipolymer comprises polymerized acrylonitrile monomer and one or more olefinically unsaturated monomers and wherein said olefinically unsaturated monomer is selected from the group consisting of methacrylonitrile, methyl acrylate, butyl acrylate, ethyl acrylate, methyl methacrylate, butyl methacrylate, vinyl acetate, styrene and its methyl derivatives, vinyl chloride, vinyl bromide, vinylidene bromide, vinylidene fluoride, sodium vinyl sulfonate, sodium methallyl sulfonate, sodium styrene sulfonate, acrylic acid, methacrylic acid, vinyl sulfonic acid, itaconic acid, ethylene, propylene, isobutylene and combinations thereof.

8. The composition of claim 1, wherein the nitrile multipolymer is an acrylonitrile olefinically unsaturated multipolymer comprising about 95% by weight to about 20% by weight polymerized acrylonitrile and about 80% by weight to about 5% by weight polymerized olefinically unsaturated monomer.

9. A process for stabilizing a high nitrile multipolymer, said process comprises the steps of polymerizing a multimonomer mixture consisting of an acrylonitrile monomer and one or more olefinically unsaturated monomer, a surfactant or suspending aid, a molecular weight modifier, a free-radical initiator, at a temperature in the range of about 40°C to about 120°C, in the substantial absence of molecular oxygen; and subsequently adding a stabilizer composition to the multipolymer wherein said stabilizer composition is selected from the group consisting of maleic acid, derivatives of maleic acid, salts of maleic acid, maleic anhydride, maleamides, salts of maleamides, maleates, salts of maleamides and combinations thereo; and wherein said stabilizer composition is added to the high nitrile multipolymer in the range of about 0.1% to about 10% by weight of the high nitrile multipolymer.

10. The process of claim 20, wherein said stabilizer composition is added to the high nitrile multipolymer in the range of about 0.2% to about 5% by weight of the high nitrile multipolymer.